“Hybrid engineering” to protect eroding coastlines in Indonesia

Demak district, Indonesia. This week will see the start of the construction of 2 permeable structures to protect the severely eroding coastline of Timbul Sloko village in Northern Java.

Wetlands International, the Indonesian Ministry for Maritime Affairs and Fisheries (MMAF) and the Dutch research institute Deltares are working together to reverse the erosion process near Timbul Sloko village, which is eroding at a fast pace and exposing the villagers to frequent flooding episodes. Deltares has designed an innovative approach to reduce erosion by using permeable structures to trap sediment along the coast and allow mangrove rehabilitation.

Two structures will be built by the MMAF based on the design prepared by Deltares and facilitated by Wetlands International Indonesia. These activities are part of a small scale experiment to test the hybrid engineering concept in severely eroding mud coasts. It is expected that each structure will take approximately 1 month to complete. After that time, the structures should start trapping sediments and creating favourable conditions for mangroves to grow in that area.

If the structures are successful and the approach is expanded, they will reclaim the land that was lost and prevent further erosion and land loss. Simultaneously, the new coastal mangrove belt will provide a range of ecosystem services, from enhanced fisheries yields to materials for construction and carbon storage.

The local fisheries service, the Diponegoro University, a local NGO (KESEMAT) and the Timbul Sloko community were involved in the baseline assessment and will be involved in the monitoring and maintenance once the structures are in place.

The permeable structures are designed to capture sediment in the same way a natural mangrove root system would. Illustration by Joost Fluitsma.

To read more about Timbul Sloko, visit the blog written by Wetlands International intern Stefan Verschure.